Indicators of variable values



Sept. 6, 1960 Y E. e. M. WILKES ETAL 2,951,462

INDICATORS 0F VARIABLE VALUES 3 Sheets-Sheet 1 Filed July 1, 1957 E. G. M. WILKES ET AL 2,951,462

INDICATORS OF VARIABLE VALUES Sept. 6, 1960 3 Sheets-Sheet 2 Filed July 1, 1957 In vemors z 6 2770255022 21/219? (fizz cry?? [2 f BY 022 4.960 2 20/22 qy Attorney p 1960 E. G. M. WILKES EI'AL 2,951,462

INDICATORS OF VARIABLE VALUES 3 Sheets-Sheet 3 Filed July 1, 1957 flay Attorney 6a a BY ZZ? $2??? zwzm United States Patent INDICATORS OF VARIABLE VALUES Edward George Marston Wilkes, Horsham, and Pasco William Ray, Norwood Hill, Horley, England, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 1, 1957, Ser. No. 668,997

Claims priority, application Great Britain July 4, 1956 9 Claims. (Cl. 116-116) This invention relates to indicators of variable values such as speed, pressure and temperature and is particularly applicable to speedometers for vehicles, and especially motor road vehicles.

The invention results in an indicator of a very simple construction in which variation in a value to be indicated is shown by an increase in one and a decrease in the other (or conversely) of two areas of contrasting colour or pattern visible through an arcuate window which may substend an angle of more than 180.

An indicator according to the invention comprises a front and a rear plate which are relatively rotatable, about an axis offset from the centre of an arcuate window in the front plate which substends an angle of more than 180", the rear plate having thereon a distinctively marked area and the degree of relative rotation of the plates being indicated by the arcuate length of the marked area presented to view through said window.

Preferably the front plate is fixed, and the rear plate is rotatable; and the distinctively marked areaon the latter has a colour or pattern diiferent from the rest of the plate and providing a sharp contrast therewith.

The scope of the invention is defined by the appended claims; how it can be performed is hereinafter particularly described with reference to the accompanying drawings, in which:

Figure 1 is a vertical section through the dashboard of a motor vehicle fitted with a speedometer according to this invention;

Figure 2 is a front elevation of the speedometer;

Figure 3 is a diagrammatic showing of a first modified speedometer dial arrangement, the parts positioned to give a maximum reading;

Figure 4 is a similar showing of a second modified arrangement at maximum reading;

Figure 5 is a showing of the first modified arrangement of Figure 3 but at zero reading;

Figure 6 is a showing of the second modified arrangement of Figure 4 but at zero reading.

The speedometer shown in Figures 1 and 2 is mounted in a housing '1 which is secured by a nut and stud 2, 3 to a stirrup 4 fixed to the dashboard 5 of a motor vehicle.

The housing 1 comprises a metal cup 6, a rear part 7 which is fixed to the cup by screws 8, and a front part 9 which is fixed to the rear part 7 by screws 10. The housing 1 is enclosed in an outer casing 11 which is forced against the dashboard 5 when the nut 2 is screwed up. The parts 7, 9 and 1 1 are conveniently made of synthetic resin or like material.

The housing 1, besides containing the speedometer, also contains a clock -12 and an odometer 14. The clock 12 is mounted in a projecting central boss 15 on the front part 9, and the odometer 14, which can be viewed through a slit 16 in the front part 9, is carried in a plate 17 which is held between co-operating flanges 18 on the opposed inner surfaces of the parts 8 and 9. The plate 17 is surrounded by a lens 19 which is also held between the flanges 18.

An opaque dished speedometer dial 20 having numerals 21 marked thereon and an arcuate slot 22 formed therein is held to the rear of the plate 17 and lens 19, between the fianges 18. The slot 22 subtends an arc of approximately 240 and is visible about the boss 15 through the lens 19, the slot 22 forming a window through which part of an indicator disc 23 can be seen.

The disc 23 is fixed to the spindle 24 of a known type of speedometer drive mechanism 25 and is adapted to be rotated with the spindle 24 through an angle in proportion to the speed to be indicated; the axis of the spindle 24 is offset from the centre 26 of the arcuate slot 22. The disc 23 is predominantly white but has thereon a red area 27 no part of which is visible through the slot 22 when the disc 23 has been rotated to its zero indication position. The area 27 is so arranged that, as the spindle 24 is rotated by the mechanism 25 to indicate an increasing speed an arcuate portion of the red area 27, of progressively increasing length, becomes visible through the slot 22. The inner edge of the area 27 is formed by an arc 28 (Fig. 2) struck about a point 29 offset from the axis of spindle 24, and the outer edge describes an are 30 struck about the axis of the spindle 24. When the disc 23 is in its maximum indication position, point 29 is coincident with the centre 26 of slot 22. It Will be understood that any other contrasting colours, or contrasting patterns may be employed for the area 27 and the remaining portion of the disc 23.

Alternative arrangements of the area 27 on the disc 23 and slot 22 are shown in Figures 3 and 5 and 4 and 6,

' parts corresponding to those shown in Figures 1 and 2 having similar reference numerals and the red area 27 being shown shaded. I

In Figure 3 the inner edge of the area 27 is formed by an varc 31 the centre 32 of which is coincident with the centre 26 of the slot 22 when the disc 23 is in its maximum indication position as shown, the radius of are 31 being substantially the same .as that of the inner edge of slot 22; the outer edge of the area 27 is formed by an are 33 having a centre aligned with the axis of the spindle 24 and a radius equal to the greatest distance from the spindle axis to the outer edge of the slot 22.

In Figure 4 the outer edge of the area 27 is formed by .an arc 34 the radius of which is substantially the same as that of the outer edge of slot 22 and the centre 35 of which, when the disc 23 is in its position of maximum indication, as shown, coincides with the centre 26 of slot 22. The inner edge of the area 27 is formed by an are '36 the centre of which is coincident with the axis of spindle 24 and the radius of which is not more than the smallest distance between the spindle axis 24 and the inner edge of the slot 22.

In all the arrangements described the relative positions of the centres must be such that when the disc is in a position to bring the wider end of the area 27 adjacent the left hand end of the slot 22, the remainder of the area 27 shall not be visible in the slot 22 but will lie to one side or the other of the slot 22, as will be evident from Figures 5 and 6, in which the discs 23 in the arrangements shown in Figures 3 and 4 are shown in positions corresponding to a zero indication. V

The boundaries of the red area 27 on the indicator disc 23 to co-operate with a given arcuate slot 22 on the dial 20 may be ascertained in the following manner: 7

It wvill be assumed that the arcuate slot 22"subtends an angle of 230 and has an inner radius of 1 /2 inches and a width of approximately A; inch, and that the spindle 24 on which the disc 23 rotates is ofiset from the centre of the arc of the slot 22 by approximately inch, the axis of spindle 24 lying on or near the radius joining the centre 26 of the arc of the slot 22 and its right-hand end. The area of the disc 23 visible through the arcuate slot 22 is then marked on the disc 23 and this operation is repeated with the disc 23 rotated anti-clockwise through successive small angular increments relativeto the dial 20, the radial line which indicates the right-hand extremity of the area of the disc 23 visible through the slot 22 in the initial position of the dial disc 23 being taken as the limit, in a clockwise direction, of the area to be coloured red on the disc 23. It Will be found that the resultant area thus defined on the disc 23 is arcuate and increases in width from one end to the other, its inner boundary having a curvature similar or approximately similar to the inner boundary of the slot 22, as shown in Figures 2, 3 and 5. 7

If the axis of rotation of the disc 23 is placed so that it lies at the same distance from the centre 26 of the slot but on or near to a radius joining the centre 26 and the left-hand end of the slot 22, then the resultant arcuate area defined by following the procedure indicated above will also increase in width from one end to the other but in this case the outer boundary of the arcuate area will be of similar, or substantially similar curvature to that of the outer boundary of the slot 22, as shown in Figures 4 and 6.

The disc 23 may be painted in contrasting colours or may be formed from a translucent coloured material, a portion of which is rendered opaque or made of a different colour and in the latter case it may be illuminated by transmitted instead of reflected light.

The dial 20 may be of transparent material with an opaque layer of paint thereon except over a region to form the window 22.

The arcuate slot 22 may, as shown, be of constant width or may be of progressively increasing width from one end to the other, so that the radial extent of the visible end of the area 27 varies with the length of the are visible through the slot 22.

As shown in Figure 2, the width of the area 27 is such that at any position of the disc 23 it extends slightly to either side thereof, in order to prevent an incorrect impression being given if the speedometer is viewed at an angle to the axis of the disc 23.

We claim:

1. An instrument, such as a speedometer, comprising a casing with a window, a driving mechanism in said casing, a rear plate mounted in said casing for rotation by said mechanism about a first axis incidental to instrument operation, said plate having two contrasting areas directed toward said window, one of said areas being arcuate with its inner border concentric with a second axis, a front plate interposed between said rear plate and said window and having an arcuate slot concentric with a third axis and adapted to register with said one area for disclosing the latter an extent to indicate the instrument reading, and said three axes being offset from one another within the area partially defined by said slot.

2. An instrument, such as a speedometer, comprising a casing with a window and enclosing a driving shaft, a rear plate mounted in said casing and connected to said shaft for rotation about a first axis, said plate having a contrasting area directed toward said window and describing an arc of more than 180", the inner border of said area being concentric with a second axis, a front plate interposed between said rear plate and said window, an arcuate slot in said front plate, said slot being concentric with a third axis and being adapted partially to register with said contrasting area when said rear plate is rotated by said shaft to indicate an instrument reading by the extent of registry, and said three axes being parallel and offset from one another.

3. An instrument comprising a casing with a window and enclosing a driving shaft, a rear plate mounted in said casing and connected to said shaft for rotation thereby and having a contrasting arcuate area directed toward said window, a front plate interposed between said rear plate and Window, an arcuate slot in said front plate extending about a given center and positioned to register with said contrasting area an extent giving an instrument reading when said rear plate is rotated, and the axis of rotation of said rear plate being offset from the said given center and partially encircled by said slot.

4. An instrument, such as a speedometer, comprising a casing with a window, a rear plate mounted in said casing, a contrasting arcuate area on said plate and directed toward said window, a front plate interposed between said rear plate and window, an arcuate slot in said front plate describing an arc of more than said area having an arcuate wedge configuration with one border substantially corresponding with one edge of said slot, said plates being relatively rotatable about different axes which are parallel and partially surrounded by said slot, and means within said casing for effecting the relative rotation.

5. An instrument, such as a speedometer, comprising a casing with a window, a rear plate mounted in said casing, a contrasting area on said plate directed toward said window, a front plate interposed between said rear plate and window, an arcuate slot in said front plate describing an arc of more than 180, one border of said area substantially corresponding with one edge of said slot, the extent of said area being adequate to register with the entire area of said slot at the highest reading of said instrument, said plates being relatively rotatable about different centers located on parallel axes partially surrounded by said slot, and means within said casing for supporting and rotating one of said plates.

6. An instrument, such as a speedometer, comprising a casing with a window, a rear substantially circular plate mounted in said casing, a contrasting area on one side of said plate directed toward said window, said area being partially defined by two opposite edges extending substantially radially on said plate and a third edge of a given radius, a front plate interposed between said rear plate and window, an arcuate slot in said front plate with one side of said slot describing an arc with substantially said given radius, said plates being relatively rotatable about different centers, means within said casing for effecting said relative rotation, and the arrangement being such that said contrasting area registers with the full length of said slot at a maximum reading of said instrument and is concealed from view by said front plate at a zero reading of said instrument.

7. An instrument such as set forth in claim 6 wherein said given radius is the inner radius of the arcuate slot.

8. An instrument such as set forth in claim 6 wherein said given radius is the outer radius of the arcuate slot.

9. An instrument such as set forth in claim 6 wherein symbols are placed on said front plate along the length of said slot, and said front plate is fixed in position.

References Cited in the file of this patent UNITED STATES PATENTS 2,309,941 Drummond Feb. 2, 1943 2,759,447 Helgeby Aug. 21, 1956 2,887,084 Sevacek May 19, 1959 FOREIGN PATENTS 496,350 Germany Apr. 22, 1930 436,710 Great Britain Oct. 16, 1935 

